Conventional hand held can openers have generally operated by severing the top of the chime portion of a can via a sharpened cutting wheel which is oriented generally vertically and positioned inside the can wall or chime. The can is typically gripped between the cutting wheel and a movable traction wheel, also oriented vertically and positioned outside the can outer wall. A number of disadvantages result from the use of such conventional can openers, including contacting of the can contents via the cutting wheel, introducing metal shavings into the can, and dropping the severed lid into the can such that it is difficult to retrieve.
More recently, hand held can openers have been developed which sever the outer seam wall of the can near the top thereof. These can openers also generally sever the can via a sharpened cutting wheel, but the cutting wheel is typically oriented substantially horizontally, albeit at a slight angle, with a movable traction wheel being oriented generally vertically and being positionable inside the outer seam wall and being selectively movable toward the cutting wheel such that the can is held between the traction wheel and the cutting wheel. A hand crank is usually provided for turning the traction wheel, which serves to rotate the can past the cutting wheel. Examples of such outer seam wall can openers include the present inventor's U.S. Pat. Nos. 5,121,546 (the "'546 patent") and 5,367,776 (the "'776 patent"), both of which are incorporated herein by reference.
As shown in FIG. 1 included herein and labeled as "PRIOR ART", in the '776 patent, a circular cutting wheel 14 and a separate circular "abutment member" 50 are both rigidly attached to a rotatable spindle 18 in a position such that the abutment member 50 abuts against and stabilizes a can outer seam wall as the cutting wheel cuts the can outer seam wall above the abutment member. The rotatable spindle is angled slightly from vertical to provide an enhanced cutting action.
A problem with the can opener shown and described in the '776 patent is the tendency for the rotatable shaft and cutting wheel to "overwear", i.e. to wear rapidly and unevenly, thus resulting in vibration and wobble of the cutting wheel. Once this overwear condition develops, vibration and wobble increase, in turn increasing the pace of wear of the shaft and cutting wheel, which action eventually ruins the can opener.
It is clear that a need exists for an improved outer seam wall can opener in which overwear is prevented, and in which wear that does occur is relatively even such that vibration and wobble are kept to a minimum.